1. Field of the Invention
The present invention relates to a method for determining a server which should respond to a service request. It can be applied for name resolution and dynamic access to services based on the location of the user.
2. Description of the Related Art
When a mobile device of a user connects to a service it first needs to find the address the node that provides the service. For services accessed over the Internet this is typically solved by DNS (Domain Name System) which translates domain names meaningful to humans into numerical identifiers associated with networking equipment or services for the purpose of locating and addressing these devices or services worldwide. The process of identifying the numerical address (IP address) of a network entity which corresponds to a DNS request is called DNS resolution. Also IMS (IP Multimedia Subsystems) often use DNS to find the server addresses.
When the mobile device which requests the service is connected to a visited network and not to the home network there usually is made a connection to the service run in the home network. This has disadvantages, in increases the costs due to the roaming and needs more network services than would be necessary if the service could be run in the visited network. It would therefore be desirable to enable service migration to the visited network in such a case, or at least to provide services closer to a roaming user even if service migration is not supported.
If the service can be provided from multiple locations a method would be desirable that can provide the address of the most appropriate service for the specific user. This depends on factors such as the user location and the server loads. Hence, when DNS is used to provide the address of the server it needs information about the location of the user to determine which server it should direct the user to.
If the DNS server can be provided with information about the location it can also be enhanced with procedures to determine the best server and provide the address of that server. Strictly speaking this would not be a normal DNS server; it could rather be seen as a different DDDS (Dynamic Delegation Discovery System) application, since a normal DNS server does not have the intelligence to choose the best server based on the user location.
In the 3GPP standards for the EPC the selection mechanisms for S-GW and P-GW are based on DNS (see 3GPP Technical Specification 29.303, Domain Name System Procedures, Stage 3 (Release 9)). These use the DNS server in the MME which uses information about the UE location, e.g. the TAI or cell-ID, to the DNS request. The mechanisms are based on Dynamic Delegation Discovery System (DDDS) (see M. Mealling, “Dynamic Delegation Discovery System (DDDS) Part One: The Comprehensive DDDS”, IETF RFC 3401, October 2002), which allows lazy binding to be implemented for DNS. This is limited to selection of these specific servers and requires these mechanisms to be implemented in the MME. It would, however, be desirable to enable that the DNS is used to direct any SPM (service program mobility) enabled service to an arbitrary server that may be located outside of the mobile network. Moreover, it would be desirable that no special support from the visited network is required which simplifies deployment of SPM.
Content delivery networks such as Akamai use DNS to direct the user to the best located server based on the location of the user (see Mukaddim Pathan and Rajkumar Buyya, “A Taxonomy of CDNs”, Content Delivery Networks, R. Buyya, M. Pathan, and A. Vakali (Eds.), Springer-Verlag, Germany, 2008.) However, the Akamai system is based on using a large number of DNS-servers and measuring the location of the user by estimating the delays between the user and different servers. A more simple and easy to implement approach would be desirable.